Glycosylation-independent targeting enhances enzyme delivery to lysosomes and decreases storage in mucopolysaccharidosis type VII mice

Abstract

Enzyme-replacement therapy is an established means of treating lysosomal storage diseases. Infused therapeutic enzymes are targeted to lysosomes of affected cells by interactions with cellsurface receptors that recognize carbohydrate moieties, such as mannose and mannose 6-phosphate, on the enzymes. We have tested an alternative, peptide-based targeting system for delivery of enzymes to lysosomes in a murine mucopolysaccharidosis type VII (MPS VII) model. This strategy depends on the interaction of a fragment of insulin-like growth factor II (IGF-II), with the IGF-II binding site on the bifunctional, IGF-II cation-independent mannose 6-phosphate receptor. A chimeric protein containing a portion of mature human IGF-II fused to the C terminus of human ␤-glucuronidase was taken up by MPS VII fibroblasts in a mannose 6-phosphate-independent manner, and its uptake was inhibited by the addition of IGF-II. Furthermore, the tagged enzyme was delivered effectively to clinically significant tissues in MPS VII mice and was effective in reversing the storage pathology. The tagged enzyme was able to reduce storage in glomerular podocytes and osteoblasts at a dose at which untagged enzyme was much less effective. This peptide-based, glycosylation-independent lysosomal targeting system may enhance enzyme-replacement therapy for certain human lysosomal storage diseases.␤-glucuronidase ͉ IGF-II͞Man6-P receptor ͉ receptor-mediated endocytosis ͉ enzyme-replacement therapy ͉ lysosomal storage disease

Enzyme therapy in mannose receptor-null mucopolysaccharidosis VII mice defines roles for the mannose 6-phosphate and mannose receptors

“…with 1 mg͞kg P-GUS weekly for 3 wk and killed 7 days later for histopathology, histochemistry, and measurement of residual enzyme levels in each organ. We have used this protocol previously to demonstrate differences in effectiveness between P-and NP-GUS and between GUS and GUS-glycosylationindependent lysosomal targeting in MR ϩ/ϩ mice (6,15). This dose is also comparable to that used in many human ERT trials (2-5).…”

Human sulfatase transiently and functionally active expressed in E. coli K12

“…(Robert et al 1998;Parodi, 2000;Helenius and Aebi, 2001;LeBowitz et al 2004); we expressed the hrIDS in E. coli K12, with the main object of biochemical studies and chemical addition of the N-glycosilation-manose-6-phosphate pattern as strategy to address the recombinant protein to the target tissue. Reasons why it is important to improve the expression of hrIDS in a suitable system as E. coli.…”

Highly Versatile Polyelectrolyte Complexes for Improving the Enzyme Replacement Therapy of Lysosomal Storage Disorders

“…22 The occurrence of the uptake via the two different mechanisms is here suggested by the enhanced internalization observed in vitro for PEC-RGD than for PEC. This opens the possibility of an alternative glycosylation independent targeting 55,57 for ERT, and might facilitate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 the use of non-glycosylated or partially glycosylated enzymes for treatment of LSD via ERT. Thus, GLA encapsulation will also endure a protection effect against GLA opsonization in the blood stream as previously demonstrated for other systems.…”